JP2009212565A - Chromatic dispersion compensation designing method in optical network, and system thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimally design a dispersion compensation amount in each chromatic dispersion compensation device so as to satisfy desired optical signal quality at a terminal node, while considering the residual chromatic dispersion during the transmission, for each wavelength path on an optical network. <P>SOLUTION: A residual chromatic dispersion target value at a terminal node is set for each wavelength path, and also, candidates of the dispersion compensation amount settable in each chromatic dispersion compensation device on the optical network are set. Computation processing is executed for selecting the dispersion compensation amount in each chromatic dispersion compensation device from the set candidates so that the sum of errors between the residual chromatic dispersion amounts and the set residual chromatic dispersion target values at the terminal nodes for all of wavelength paths becomes minimum. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for compensating for chromatic dispersion in an optical network. In particular, the present invention relates to a chromatic dispersion compensation design method and system for optimizing the compensation amounts of a plurality of chromatic dispersion compensators arranged on an optical network.

  In recent years, in the field of optical networks to which wavelength division multiplexing (WDM) technology is applied, an optical add / drop multiplexer (OADM) device that realizes wavelength unit branch insertion and path switching while maintaining an optical signal, By implementing a wavelength cross-connect (WXC) device, also called an optical hub, an optical network having a complicated topology such as ring interconnection or mesh can be configured.

  In such an optical network, there is chromatic dispersion as one of the factors that determine the transmission quality of an optical signal. In order to suppress the waveform degradation of the optical signal due to the influence of this chromatic dispersion, the end-to-end of the path (hereinafter referred to as the wavelength path) through which the optical signal of each wavelength transmitted through the optical network passes. The chromatic dispersion compensator is appropriately arranged in the middle of the optical transmission line so that the residual chromatic dispersion value over the optical path is within the dispersion tolerance at the end (receiving end) of the wavelength path. . Therefore, the design for determining the dispersion compensation amount of each chromatic dispersion compensator plays an important role in determining the transmission quality of the optical signal.

  Conventionally, as a chromatic dispersion compensation design method for ring interconnections and mesh networks, for example, in Patent Documents 1 and 2 below, a method for determining a dispersion compensation amount according to a dispersion compensation map has been proposed. However, there are errors between the design value and actual value of the chromatic dispersion of the optical fiber used in the optical transmission line, and dispersion compensation errors that occur because the chromatic dispersion compensator generally has a discrete dispersion compensation amount. Since the accumulation of these errors differs for each wavelength path, there is a problem that it is difficult to realize chromatic dispersion compensation that matches a desired dispersion compensation map for all wavelength paths on the optical network.

As a conventional technique for solving this problem, for example, in the invention disclosed in Patent Document 3 below, all residual chromatic dispersion at each end point of a plurality of wavelength paths extracted from an optical network having a complicated topology is used. Discloses a design method and a system for determining a dispersion compensation amount of a chromatic dispersion compensator provided in each wavelength path so that the wavelength is within an allowable residual chromatic dispersion range set for all wavelength paths. . In this conventional design method, for each wavelength path, the chromatic dispersion value (constant) of the optical fiber along the wavelength path, and the dispersion compensation amount (variable) of each chromatic dispersion compensator arranged on the wavelength path. ) To be within the preset allowable residual chromatic dispersion range (constant), solve the simultaneous inequality for all wavelength paths, and the dispersion compensation amount of each chromatic dispersion compensator It is determined whether or not a solution exists.
US Pat. No. 6,580,861 JP 2004-274615 A International Publication No. 2005/006604 Pamphlet

However, the following problems remain in the conventional chromatic dispersion compensation design method as described above.
First, in the conventional design method, the solution of the dispersion compensation amount of each chromatic dispersion compensator obtained by simultaneous inequality is given within a required range. Therefore, when there are a plurality of combinations of dispersion compensation amounts of the respective chromatic dispersion compensators, there is a problem that a specific solution is not shown as to which combination should be selected from the combinations.

  Secondly, in the conventional design method, only the condition that the residual chromatic dispersion at each termination point is within a preset allowable residual chromatic dispersion range for each wavelength path is considered. Under such conditions, residual chromatic dispersion in the middle of each wavelength path is not taken into consideration, so a dispersion compensation amount may be set such that optical signal degradation due to residual chromatic dispersion in the middle of transmission becomes significant. Even if chromatic dispersion compensation is performed at the terminal point as designed, it may be difficult to recover the quality of the optical signal.

  The present invention has been made paying attention to the above points. For a plurality of wavelength paths set on an optical network, the termination of each wavelength path is considered while taking into account residual chromatic dispersion during transmission of each wavelength path. Disclosed is a chromatic dispersion compensation design method in an optical network and a system thereof, which can determine the dispersion compensation amount of each chromatic dispersion compensator arranged on the network so as to satisfy a desired optical signal quality at the node. For the purpose.

  In order to achieve the above object, the present chromatic dispersion compensation design method is provided for an optical network having a plurality of nodes connected to each other via an optical transmission line, from a start node to a plurality of optical signals transmitted through the optical network. A chromatic dispersion compensation design method for setting a compensation amount of chromatic dispersion compensation performed on a plurality of wavelength paths indicating a route to a node, comprising: (A) inputting optical network information; Based on the optical network information, for each wavelength path, a process of setting a residual chromatic dispersion target value at the terminal node, and (C) a candidate for a dispersion compensation amount in a plurality of chromatic dispersion compensators arranged on each wavelength path And (D) each of the above so that the sum of errors between the residual chromatic dispersion value at the terminal node and the residual chromatic dispersion target value for all wavelength paths is minimized. A process of executing the operation process of selecting the dispersion compensation amount of the long dispersion compensator from among the candidates, a method of containing.

  In addition, the present chromatic dispersion compensation design system provides a path from a start node to a terminal node of a plurality of optical signals transmitted through the optical network, for an optical network having a plurality of nodes connected to each other through an optical transmission path. A chromatic dispersion compensation design system for setting a compensation amount of chromatic dispersion compensation performed on a plurality of wavelength paths shown, wherein input means for inputting optical network information, and optical network information inputted by the input means Based on the target value setting means for setting the residual chromatic dispersion target value in the terminal node for each wavelength path, and candidates for setting the dispersion compensation amount candidates in the plurality of chromatic dispersion compensators arranged on each wavelength path A residual chromatic dispersion value at a termination node for all wavelength paths and a residual chromatic dispersion target value set by the target value setting means. Such that the sum of the differences is minimized, but with a, operating means for executing arithmetic processing of selecting the dispersion compensation amount of each of the chromatic dispersion compensator from the candidates set by the candidate setting unit.

  According to the chromatic dispersion compensation design method and its system in an optical network as described above, even in an optical network having a complicated topology such as a mesh, all wavelength paths set on the optical network are in the middle of transmission. It is possible to easily design the optimum dispersion compensation amount of each chromatic dispersion compensator that can satisfy the desired optical signal quality at the terminal node while suppressing the residual chromatic dispersion in the range within a required range. As a result, it is possible to minimize degradation of optical signal quality due to chromatic dispersion in all wavelength paths on the optical network, and as a result, the number of regenerative repeaters required in the optical network is minimized. Design that leads to cost reduction is possible.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a diagram showing a hardware configuration in an embodiment of a chromatic dispersion compensation design system according to the present invention.

  In FIG. 1, the present chromatic dispersion compensation design system includes an input device 11, an output device 12, a drive device 13, an auxiliary storage device 14, a memory device 15, an arithmetic processing device 16, and a database 17. These are connected to each other by a system bus 18. Although this chromatic dispersion compensation design system can be configured as a dedicated device, for example, a general-purpose personal computer, a workstation or the like can be applied.

  Specifically, the input device 11 has a keyboard and a mouse operated by the user, and inputs various data. The output device 12 has a display for displaying various windows and data necessary for operating the program of the chromatic dispersion compensation design system, and is displayed based on the execution program. Here, in the present invention, the execution program installed in the chromatic dispersion compensation design system is provided by the recording medium 19 such as a CD-ROM, for example. The recording medium 19 on which the program is recorded is mounted on the drive device 13, and the execution program stored in the storage medium 19 is installed from the recording medium 19 to the auxiliary storage device 14 via the drive device 13.

  The arithmetic processing device 16 controls processing of the entire chromatic dispersion compensation design system including various operations and each processing described later, based on the execution program read and stored by the memory device 15. Various information necessary during the execution of the program can be acquired from the database 17 and can be stored.

FIG. 2 is a diagram showing a configuration example of an optical network to which the chromatic dispersion compensation design method of the present invention is applied and an example of a dispersion compensation map.
The optical network shown on the upper side of FIG. 2 includes, for example, seven nodes N1 to N7 connected in a mesh shape via an optical transmission line, and a chromatic dispersion compensator (not shown) is included in each of the nodes N1 to N7. (DCM: Dispersion Compensation Module). On this optical network, in the illustrated example, a wavelength path WP1 in which the optical signal is transmitted from the starting node N1 to the terminal node N2 without passing through another node, and the optical signal is transmitted from the starting node N1 to the node. A wavelength path WP2 that is transmitted to the terminal node N2 via N5 and N3, a wavelength path WP3 that transmits an optical signal from the starting node N1 to the terminal node N3 via the node N5, and an optical signal A wavelength path WP4 transmitted from the start node N1 to the end node N7 via the nodes N5 and N6 is set. Operations of the nodes N1 to N7 are centrally managed by a network management system (NMS). The dispersion compensation map illustrated on the lower side of FIG. 2 is an optimum dispersion compensation map for the wavelength path WP4 determined by the chromatic dispersion compensation design method of the present invention described in detail later. In the optimum dispersion compensation map of this wavelength path WP4, −800 ps / nm is set as the dispersion compensation amount of DCM at the node N5, −150 ps / nm is set as the dispersion compensation amount of DCM at the node N6, and the DCM of the DCM at the node N7 is set. The dispersion compensation amount is set to -800 ps / nm.

Next, an example of processing executed in the above chromatic dispersion compensation design system will be described in detail with reference to the flowchart of FIG.
In this chromatic dispersion compensation design system, first, network information is input in step 11 (indicated by S11 in the figure, and the same shall apply hereinafter), parameters of each wavelength path are set in step 12, and step 13 is further performed. To set parameters for each chromatic dispersion compensator. Then, using each set parameter, the dispersion compensation amount of each chromatic dispersion compensator is designed (calculation processing) in step 14, and the design result is output in step 15. Hereinafter, details of the processing in each step will be specifically described.

  In the input of the network information in step 11, the network information necessary for designing the chromatic dispersion compensation amount is input by the user using the input device 11 (FIG. 1) for the optical network to be designed. The network information includes network topology information, node information, span information, and wavelength path information.

  Specifically, the network topology information includes, for example, information on the arrangement of nodes on the optical network and the connection state between the nodes. The node information includes information regarding the type or function of each node (for example, an OADM node or an optical amplification relay node). In the optical network illustrated in FIG. 2, a chromatic dispersion compensator is arranged at each node, so that each node also has a function as a dispersion compensation node in addition to functions such as an OADM node and an optical amplification relay node. Will be. However, since the present invention does not necessarily require that all nodes on the optical network have a dispersion compensation function, it is sufficient that the presence or absence of the dispersion compensation function of each node is clarified by the above node information. The span information includes information on optical fibers (for example, fiber type, fiber length, chromatic dispersion value, transmission loss, etc.) used in an optical transmission line (hereinafter referred to as a span) connecting adjacent nodes. It is done. The wavelength path information includes the path information of each optical signal transmitted over the optical network, the signal type (for example, 2.4 Gbps, 10 Gbps, 40 Gbps, or 100 Gbps), wavelength information, and output power information of the optical signal from each node. There is. One wavelength path includes an optical signal of one wavelength or a plurality of wavelengths transmitted through the same route. When setting parameters or the like to be described later for a plurality of wavelength paths set on the optical network, each wavelength is set. A standard wavelength representative of the optical signal transmitted through the path is used. As this standard wavelength, for example, the center wavelength of the signal wavelength band can be determined in advance.

  Note that the network information input in the present invention is not limited to the above specific example, and any type may be used as long as it is information related to each parameter used for calculation processing of chromatic dispersion compensation design described later.

  Next, in the parameter setting of each wavelength path in Step 12, based on the network information input in Step 11 above, as the parameters of each wavelength path necessary for the chromatic dispersion compensation design, the tolerance at the end node of each wavelength path is set. The residual chromatic dispersion range (chromatic dispersion tolerance) and the residual chromatic dispersion target value at the terminal node of each wavelength path are set.

  Specifically, the allowable residual chromatic dispersion range includes the path information of each wavelength path, node information along the path, fiber information between nodes on the path, and the signal type of the optical signal transmitted through each wavelength path. Based on the output power information of the optical signal from each node, an allowable residual chromatic dispersion range at the terminal node is obtained. This allowable residual chromatic dispersion range is basically the same design parameter as the allowable residual chromatic dispersion range at the termination point in the conventional chromatic dispersion compensation design method described above. On the other hand, the residual chromatic dispersion target value is newly set as a design target value for residual chromatic dispersion within the allowable residual chromatic dispersion range determined above. This residual chromatic dispersion target value is preferably set inside the intermediate portion excluding the upper and lower limits of the allowable residual chromatic dispersion range. Specifically, the allowable chromatic dispersion target value obtained using the following equation (1) It is possible to set to the midpoint of the residual chromatic dispersion range.

ここで、ＲＤｔａｒｇｅｔ［ｉ］は、波長パスｉの残留波長分散目標値であり、ＲＤｔｏｌｅｒａｎｃｅ＿ｕｐｐｅｒ[ｉ］は、波長パスｉの許容残留波長分散範囲の上限値であり、ＲＤｔｏｌｅｒａｎｃｅ＿ｌｏｗｅｒ[ｉ］は、波長パスｉの許容残留波長分散範囲の下限値である。なお、本発明における残留波長分散目標値の設定は、許容残留波長分散範囲の中点に限定されるものではなく、上記の（１）式は残留波長分散目標値の一例を示しているに過ぎない。

Here, RDtarget [i] is a residual chromatic dispersion target value of wavelength path i, RDtolerance_upper [i] is an upper limit value of an allowable residual chromatic dispersion range of wavelength path i, and RDtolerance_lower [i] is a wavelength path. This is the lower limit value of the allowable residual chromatic dispersion range of i. The setting of the residual chromatic dispersion target value in the present invention is not limited to the midpoint of the allowable residual chromatic dispersion range, and the above equation (1) merely shows an example of the residual chromatic dispersion target value. Absent.

  Next, in step 13 parameter setting of each chromatic dispersion compensator, each wavelength required for chromatic dispersion compensation design is determined based on the network information input in step 11 and the parameters of each wavelength path set in step 12. As a parameter of the dispersion compensator, a dispersion compensation amount candidate (hereinafter, may be abbreviated as “DCM candidate”) of the chromatic dispersion compensator arranged at each node is set. As a DCM candidate setting method, for example, it is preferable to follow at least one of the following three methods.

  In the first technique, as a chromatic dispersion compensator of each node, for example, a case where a dispersion compensation fiber module capable of discretely changing a dispersion compensation amount by switching and connecting a plurality of dispersion compensation fibers is used. Suppose. In this case, the insertion loss of the chromatic dispersion compensator changes according to the dispersion compensation amount set in the chromatic dispersion compensator. Pay attention to the change in insertion loss according to the amount of dispersion compensation. For example, when a chromatic dispersion compensator is placed at the input stage of an optical amplifier, it passes through the chromatic dispersion compensator after being transmitted through the optical transmission line. The candidates for the amount of dispersion compensation of the chromatic dispersion compensator are set so that the power of the optical signal falls within the input dynamic range of the optical amplifier. When the chromatic dispersion compensator is disposed between the stages of the optical amplifier having a multi-stage configuration, the dispersion compensation amount of the chromatic dispersion compensator is set in accordance with the insertion loss allowed between the stages of the optical amplifier. Can be set.

  Specifically, for example, as shown in FIG. 4, a chromatic dispersion compensator (DCM) 24 is arranged at the input stage of the reception-side optical amplifier 25, and the transmission-side optical amplifier 21 and the optical transmission line 22 are arranged. The first method will be described in detail, assuming a configuration in which the optical signal transmitted to is input to the DCM 4 via the connector 3 connecting the optical transmission line 22 and the DCM 24. In such a span configuration, the output power of the optical signal from the optical amplifier 21 on the transmission side (input power of the optical signal to the optical transmission line 22) is Pout, the loss of the optical transmission line 22 is LOSfiber, and the connector 23 When the connection loss is LOSconnector and the upper and lower limits of the input dynamic range of the optical amplifier 25 on the receiving side are DR_upper and DR_lower, the range of insertion loss of the DCM 24 allowed in the span is LOSdcm_upper, The lower limit value is given by the following equation (2), with LOSdcm_lower.

図４中に示した例では、ＤＣＭ２４の挿入損失許容範囲の上限値ＬＯＳｄｃｍ＿ｕｐｐｅｒが５．７ｄＢ、下限値ＬＯＳｄｃｍ＿ｌｏｗｅｒが１．７ｄＢとなっている。このＤＣＭ２４の挿入損失許容範囲に従って、例えば図５に示すようなＤＣＭ２４の離散的な分散補償量と挿入損失との対応関係を保持したＤＣＭテーブルより、ＤＣＭ２４の分散補償量の候補が選択される。すなわち、ここでは−１５０ｐｓ／ｎｍから−９００ｐｓ／ｎｍまでの分散補償量がＤＣＭ候補として設定される。なお、光ネットワーク上の各ＤＣＭに対応したＤＣＭテーブルは、例えば、前述したステップ１１（図３）のネットワーク情報の入力の際にノード情報若しくはスパン情報の一部として与えられ、データベース１７（図１）に格納されるようにしておけばよい。

In the example shown in FIG. 4, the upper limit value LOSdcm_upper of the allowable insertion loss range of the DCM 24 is 5.7 dB, and the lower limit value LOSdcm_lower is 1.7 dB. According to the allowable insertion loss range of the DCM 24, for example, a candidate for the dispersion compensation amount of the DCM 24 is selected from a DCM table holding the correspondence between the discrete dispersion compensation amount of the DCM 24 and the insertion loss as shown in FIG. That is, here, a dispersion compensation amount from −150 ps / nm to −900 ps / nm is set as a DCM candidate. Note that the DCM table corresponding to each DCM on the optical network is given as part of node information or span information when the network information is input in step 11 (FIG. 3), for example, and the database 17 (FIG. 1). ).

  In the second method, a span in which a chromatic dispersion compensator is arranged among a plurality of spans existing on the optical network (in the example of the optical network shown in FIG. 2, each node is provided with a chromatic dispersion compensator. Assuming the residual chromatic dispersion target value corresponding to the wavelength path (or each wavelength path when there are multiple spans) individually for all spans), the range including all the residual chromatic dispersion target values Is set as a DCM candidate corresponding to the span. In the case of a span in which no chromatic dispersion compensator is arranged, the span connected to the span and where the chromatic dispersion compensator is arranged is handled as one span.

  FIG. 6 is an explanatory diagram specifically showing a DCM candidate setting method according to the second method. Here, in order to make the explanation easy to understand, a linear network in which nodes A to J are cascade-connected as shown in the lowermost stage of FIG. 6 is assumed. Among the above nodes A to J, nodes A, D, G, and J are OADM nodes, and nodes B, C, E, F, H, and I are optical amplification relay nodes. Wavelength paths include a wavelength path WP1 (bold solid line) from node A to node D, a wavelength path WP2 (bold broken line) from node A to node J, and a path from node D to node G. It is assumed that the wavelength path WP3 (thin broken line) and the wavelength path WP4 (one-dot chain line) between the node D and the node J are set.

  First, as shown in <1-1> in the uppermost stage in FIG. 6 and <1-2> in the right side of the second stage, the residual chromatic dispersion at the termination node set in step 12 described above for each of the wavelength paths WP1 to WP4. Using the target value, the slope of residual chromatic dispersion corresponding to each of the wavelength paths WP1 to WP4 is determined. Specifically, here, when the residual chromatic dispersion target value at the terminal node of the wavelength path WPi (i = 1, 2, 3, 4) is RDtarget [i] and the distance of the wavelength path WPi is L [i], The slope RDtarget_slope [i] is obtained by the following equation (3).

なお、図６の＜１−１＞および＜１−２＞に示している平行な２本の細実線は許容残留波長分散範囲の上限値および下限値を表し、また、点線は許容残留波長分散範囲の中点を表している。

Note that two parallel thin solid lines shown in <1-1> and <1-2> in FIG. 6 represent the upper limit value and the lower limit value of the allowable residual chromatic dispersion range, and the dotted line indicates the allowable residual chromatic dispersion. Represents the midpoint of the range.

  Next, as shown in <2> in the third row of FIG. 6, for every span SPl (l = 1, 2,..., 9) between nodes A to J, all wavelengths passing through that span SPl. For the path WPi, the residual chromatic dispersion target value at the receiving side node of the span SP1 is determined. Specifically, the residual chromatic dispersion slope RDtarget_slope [i] corresponding to each wavelength path WPi obtained by the above equation (3) is applied to each span SPl, and the span SPl distance is defined as Lspan [l]. In this case, the residual chromatic dispersion target value RDtarget [i, l] of the wavelength path WPi at the receiving side node of the span SP1 is obtained by the following equation (4).

続いて、図６の２段目左側の＜３＞に示すように、上記の（４）式で求めた残留波長分散目標値ＲＤｔａｒｇｅｔ［ｉ，ｌ］を用いて、各スパンＳＰｌに対応したＤＣＭ候補を設定する。具体的に、スパンＳＰｌを通過する波長パスＷＰｉの数がｎ本であった場合、残留波長分散目標値ＲＤｔａｒｇｅｔ［ｉ，ｌ］はｎ個存在することになる。図６の例では、スパンＳＰ１，ＳＰ２，ＳＰ３，ＳＰ７，ＳＰ８，ＳＰ９は残留波長分散目標値ＲＤｔａｒｇｅｔ［ｉ，ｌ］が２個ずつ存在し、スパンＳＰ４，ＳＰ５，ＳＰ６は残留波長分散目標値ＲＤｔａｒｇｅｔ［ｉ，ｌ］が３個ずつ存在することになる。図６の＜３＞には一例としてスパンＳＰ４の様子が拡大して示してある。スパンＳＰ４では、波長パスＷＰ３に対応した残留波長分散目標値（細破線）が最大値ＲＤｔａｒｇｅｔ＿ｍａｘ＝ＲＤｔａｒｇｅｔ［３，４］となり、波長パスＷＰ２に対応した残留波長分散目標値（太破線）が最小値ＲＤｔａｒｇｅｔ＿ｍｉｎ＝ＲＤｔａｒｇｅｔ［２，４］となる。なお、図中の点ＤｓｐａｎはスパンＳＰ４の波長分散値を示している。ここで、スパンＳＰｌについて、残留波長分散目標値ＲＤｔａｒｇｅｔ［ｉ，ｌ］を全て包含する波長分散補償量の範囲をＤＣＭｒａｎｇｅ［ｌ］を考えると、該ＤＣＭｒａｎｇｅ［ｌ］は次の（５）式に示す不等式で表すことができる。

Subsequently, as shown in <3> on the left side of the second stage of FIG. 6, using the residual chromatic dispersion target value RDtarget [i, l] obtained by the above equation (4), the DCM corresponding to each span SPl Set candidates. Specifically, when the number of wavelength paths WPi passing through the span SPl is n, there are n residual chromatic dispersion target values RDtarget [i, l]. In the example of FIG. 6, there are two residual chromatic dispersion target values RDtarget [i, l] for each of the spans SP1, SP2, SP3, SP7, SP8, and SP9, and the residual chromatic dispersion target values RDtarget for the spans SP4, SP5, and SP6. There are three [i, l]. <3> in FIG. 6 shows an enlarged view of the span SP4 as an example. In the span SP4, the residual chromatic dispersion target value (thin broken line) corresponding to the wavelength path WP3 is the maximum value RDtarget_max = RDtarget [3,4], and the residual chromatic dispersion target value (thick broken line) corresponding to the wavelength path WP2 is the minimum value. RDtarget_min = RDtarget [2, 4]. The point Dspan in the figure indicates the chromatic dispersion value of the span SP4. Here, for the span SP1, when DCMrange [l] is considered as the range of the chromatic dispersion compensation amount including all the residual chromatic dispersion target values RDtarget [i, l], the DCMrange [l] is expressed by the following equation (5). It can be represented by the inequality shown.

そこで、上記の（５）式の関係を満足するようなＤＣＭの分散補償量をスパンＳＰｌのＤＣＭ候補として設定する。例えば、スパンＳＰｌに設けられるＤＣＭの分散補償量が５０ｐｓ／ｎｍ刻みで−５０ｐｓ／ｎｍから−１０００ｐｓ／ｎｍまで存在し、上記の（５）式で求まるＤＣＭｒａｎｇｅ［ｌ］が−４３０ｐｓ／ｎｍ≦ＤＣＭｒａｎｇｅ［ｌ］≦−２８０ｐｓ／ｎｍであった場合、ＤＣＭ候補としては｛−３００，−３５０，−４００｝ｐｓ／ｎｍが設定されることになる。

Therefore, a dispersion compensation amount of DCM that satisfies the relationship of the above equation (5) is set as a DCM candidate of the span SP1. For example, the dispersion compensation amount of DCM provided in the span SP1 exists from −50 ps / nm to −1000 ps / nm in increments of 50 ps / nm, and DCMrange [l] obtained by the above equation (5) is −430 ps / nm ≦ DCrange When [l] ≦ −280 ps / nm, {−300, −350, −400} ps / nm is set as the DCM candidate.

  For the DCM candidates set according to the second method, as shown in the first method, the insertion loss at the dispersion compensation amount corresponds to the input dynamic range of the optical amplifier. It is also desirable to consider.

  In the third method, as a DCM candidate setting method obtained by simplifying the second method, for example, as shown in FIG. 7, it is assumed that the residual chromatic dispersion target value of each span depends only on the span distance. Suppose that the residual chromatic dispersion target value RDtarget [l] of the span SPl is given by a linear expression having the span distance Lspan [l] as a variable as shown in the following expression (6).

ここで、ａは残留波長分散目標値のスパン距離に対する傾きを示す定数、ｂ［ｌ］はスパンＳＰｌの送信側ノードにおける残留波長分散目標値のオフセット値を示す定数である。なお、図７にはｂ［ｌ］＝０の一例が示してある。この場合、スパンＳＰｌでは、上記（６）式で与えられる残留波長分散目標値ＲＤｔａｒｇｅｔ［ｌ］を包含し、かつ、予め設定しておいたＲＤｔａｒｇｅｔ［ｌ］に対する許容誤差±ＲＤｅｒｒｏｒの範囲をＤＣＭｒａｎｇｅ［ｌ］と定め、該ＤＣＭｒａｎｇｅ［ｌ］内となる分散補償量をＤＣＭ候補として設定する。

Here, a is a constant indicating the slope of the residual chromatic dispersion target value with respect to the span distance, and b [l] is a constant indicating the offset value of the residual chromatic dispersion target value at the transmitting side node of the span SP1. FIG. 7 shows an example of b [l] = 0. In this case, the span SPl includes the residual chromatic dispersion target value RDtarget [l] given by the above equation (6), and the range of allowable error ± RDerror for the preset RDtarget [l] is DCMrange [ l], and a dispersion compensation amount within the DCMrange [l] is set as a DCM candidate.

  As for the DCM candidates set according to the third method, the insertion loss at the dispersion compensation amount corresponds to the input dynamic range of the optical amplifier as shown in the first method. It is also desirable to consider.

  When the setting of the DCM candidates is completed as described above, next, the dispersion compensation amount design (calculation processing) of each chromatic dispersion compensator in step 14 (FIG. 3) is executed. In step 14, using the parameters obtained in steps 11 to 13, the optimum value of the dispersion compensation amount of each chromatic dispersion compensator on the optical network is determined by a calculation process considering all wavelength paths. Here, as an example, a case where linear programming is applied in order to obtain an optimum solution of the dispersion compensation amount of each chromatic dispersion compensator is shown.

  In this case, the objective function in linear programming is “the difference between the residual chromatic dispersion value at the end node of each wavelength path and the residual chromatic dispersion target value set in step 12, that is, the compensation error of the residual chromatic dispersion for each wavelength path”. Is set to “minimize the sum of compensation errors of all wavelength paths”, and “a dispersion compensation amount that can be set in the chromatic dispersion compensator corresponding to each span is set as a constraint condition in the linear programming method in step 13. “Set as DCM candidate” is set.

  Such an objective function and constraint conditions can be described by, for example, relational expressions as shown in the following equations (7) and (8).

ここで、ｐｏｓＲＤｅｒｒｏｒ［ｉ］は、波長パスＷＰｉの終端ノードにおける、残留波長分散値と残留波長分散目標値との誤差が正の場合の補償誤差量を示し、ｎｅｇＲＤｅｒｒｏｒ［ｉ］は、波長パスＷＰｉの終端ノードにおける、残留波長分散値と残留波長分散目標値との誤差が負の場合の補償誤差量を示している。また、｜ｚ［ｌ］｜は、スパンＳＰｌに対応したＤＣＭの分散補償量の絶対値を示し（一般的にＤＣＭの分散補償量は負値である）、｜ＤＣＭ＿ｕｐｐｅｒ［ｌ］｜および｜ＤＣＭ＿ｌｏｗｅｒ［ｌ］｜は、前述したステップ１３でＤＣＭ候補を設定する際に求めたスパンＳＰｌでの波長分散補償量の範囲ＤＣＭｒａｎｇｅ［ｌ］の上限値および下限値の絶対値をそれぞれ示している。つまり、制約条件の第１および第２の関係式の左辺は、ステップ１３で設定したＤＣＭ候補を表している。さらに、Ｄｓｐａｎ［ｌ］は、スパンＳＰｌの波長分散値を示しており、制約条件の第３および第４の関係式の左辺第一項は、各波長パスＷＰｉの終端ノードにおける残留波長分散を表し、左辺第二項のｎｅｇＲＤｅｒｒｏｒ［ｉ］およびｐｏｓＲＤｅｒｒｏｒ［ｉ］は前記のとおり補償誤差量を示している。なお、第３および第４の関係式の右辺のＲＤｔａｒｇｅｔ［ｉ］は、ステップ１２で設定した波長パスＷＰｉの終端ノードにおける残留波長分散目標値である。

Here, posRDerror [i] indicates the compensation error amount when the error between the residual chromatic dispersion value and the residual chromatic dispersion target value is positive at the terminal node of the wavelength path WPi, and negRError [i] is the wavelength path WPi. This shows the compensation error amount when the error between the residual chromatic dispersion value and the residual chromatic dispersion target value is negative at the terminal node. | Z [l] | indicates the absolute value of the dispersion compensation amount of DCM corresponding to the span SPl (generally, the dispersion compensation amount of DCM is a negative value). | DCM_upper [l] | and | DCM_lower [L] | indicates the absolute value of the upper limit value and the lower limit value of the chromatic dispersion compensation amount range DCMrange [l] in the span SPl obtained when setting the DCM candidates in Step 13 described above. That is, the left sides of the first and second relational expressions of the constraint conditions represent the DCM candidates set in step 13. Further, Dspan [l] indicates the chromatic dispersion value of the span SP1, and the first term on the left side of the third and fourth relational expressions of the constraint condition represents the residual chromatic dispersion at the terminal node of each wavelength path WPi. In the second term on the left side, negRError [i] and posRDError [i] indicate the compensation error amount as described above. Note that RDtarget [i] on the right side of the third and fourth relational expressions is the residual chromatic dispersion target value at the terminal node of the wavelength path WPi set in step 12.

Further, here, z [l] is expressed by the following relational expression, and the above can be solved by a mixed integer programming (MIP) which is one of linear programming methods.
z [l] = x [l] · DcmStep
Here, DcmStep indicates the step size of the dispersion compensation amount of the chromatic dispersion compensator (DCM), and x [l] is an integer value. As a result, a chromatic dispersion compensator (DCM) having a discrete dispersion compensation amount (a step size of the compensation amount is DcmStep [ps / nm]) can be supported.

  By setting the objective function and constraints in linear programming or mixed integer programming in this way, it is possible to easily calculate the optimal dispersion compensation amount of DCM at each node using general mathematical programming software. can do.

  When the optimal solution of the dispersion compensation amount of each DCM is calculated by linear programming or mixed integer programming as described above, the calculation result is output to the output device 12 or the like in step 15 (FIG. 3). Then, the optimum value of the dispersion compensation amount of each DCM obtained by the present chromatic dispersion compensation design system is transmitted to each node via a network management system (NMS) that centrally manages all the nodes on the optical network, etc. The dispersion compensation amount of each DCM is set to an optimum value (see FIG. 2).

  As described above, according to the chromatic dispersion compensation design system, even in an optical network having a complicated topology such as a mesh, all wavelength paths set on the optical network remain in each span during transmission. It is possible to easily realize the optimum design of chromatic dispersion compensation capable of satisfying a desired optical signal quality at the terminal node while suppressing the chromatic dispersion within a required range. As a result, it is possible to minimize degradation of optical signal quality due to chromatic dispersion in all wavelength paths on the optical network, and as a result, the number of regenerative repeaters required in the optical network is minimized. Design that leads to cost reduction is possible.

Next, a preferred application example of the chromatic dispersion compensation design method according to the present invention as described above will be described with reference to the flowchart of FIG.
In the chromatic dispersion compensation design method shown in FIG. 8, after executing the above-described series of processing from step 11 to step 14, step 21 for verifying the design result in step 14 is added. When it is found that a path exists, a step 22 for adding a constraint condition corresponding to the path is provided, and the arithmetic processing by the mixed integer programming in step 14 is executed again. Note that the processing in each of steps 11 to 15 in FIG. 8 is the same as that described above, and thus description thereof is omitted here.

  In step 21, the optical transmission characteristics of each wavelength path are evaluated using the design result of the dispersion compensation amount of each DCM calculated in step 14, and whether chromatic dispersion compensation design is successful for all wavelength paths, that is, It is determined whether or not predetermined optical transmission characteristics required in the optical network are satisfied. If it is determined that the design is successful for all the wavelength paths, the design result is output in step 15, while there is a wavelength path whose design has failed due to the influence of chromatic dispersion. If so, the process proceeds to step 22.

  In step 22, a constraint expression for “do not select a combination of chromatic dispersion compensation amounts selected in all spans through which a wavelength path that has failed in design” is added as a constraint condition in step 14. That is, in the processing of step 14 described above, since the objective function is to minimize the dispersion compensation error of all wavelength paths, the dispersion compensation amount of DCM corresponding to each span takes a discrete value ( For example, when a dispersion compensation fiber module is used as a DCM), a residual that is realized at the end node of the wavelength path by combining the dispersion compensation amounts of the DCMs calculated in step 14 for a certain wavelength path. There is a possibility that the chromatic dispersion value does not fall within the allowable residual chromatic dispersion range. Therefore, by adding a feedback process (steps 21 and 22) including verification of the design result, it is possible to obtain a design result in which the residual chromatic dispersion value of each wavelength path is within the allowable residual chromatic dispersion range. Enables high chromatic dispersion compensation design.

  Specifically, after the feedback processing, the constraint condition in the mixed integer programming that is processed in step 14 can be described by the relational expressions as shown in the following equations (9) and (10), for example. The constraint equation that can be added to the wavelength path that has been determined to be a design failure in Step 21 is Equation (10). Note that the above equation (7) is applied to the objective function in the mixed integer programming after the feedback processing.

ここで、上記の（９）式および（１０）式を含めたステップ１４における演算処理で用いられる各記号についての説明を表１に纏めておく。

Here, Table 1 summarizes the explanation of each symbol used in the arithmetic processing in step 14 including the above equations (9) and (10).

上記の（９）式において、波長パスＷＰｉの終端ノードにおける残留波長分散値を示すＴＥＲＭ［ｉ］は、具体的には、次の（１１）式で記述される。

In the above equation (9), TERM [i] indicating the residual chromatic dispersion value at the terminal node of the wavelength path WPi is specifically described by the following equation (11).

さらに、上記の（１０）式に用いられている、波長パスＷＰｉに対応したＤＣＭの数ＮＵＭｄｃｍ［ｉ］は、具体的には、次の（１２）式で記述される。

Further, the number of DCMs NUMdcm [i] corresponding to the wavelength path WPi used in the above equation (10) is specifically described by the following equation (12).

ここで、上記の（９）式〜（１２）式を用いた演算処理に関して、具体的な一例を挙げて詳しく説明する。ここでは、例えば図９の上段に示すように、始端ノードＡから終端ノードＤに至る波長パスＷＰ１（ｉ＝１）を想定し、ノードＡ，Ｂ間のスパンＳＰ１に対応したノードＢ内のＤＣＭ候補として｛−４５０，−４００，−３５０｝が設定され、ノードＢ，Ｃ間のスパンＳＰ２に対応したノードＣ内のＤＣＭ候補として｛−２００，−１５０｝が設定され、ノードＣ，Ｄ間のスパンＳＰ３に対応したノードＤ内のＤＣＭ候補として｛−１０００，−９００，−８００｝が設定されているものとする。そして、先のステップ１４における演算処理により、波長パスＷＰ１についてのＤＣＭの分散補償量の最適解として、例えば、スパンＳＰ１に対応したＤＣＭの分散補償量Ｄｄｃｍを−４００ｐｓ／ｎｍ（ｌ＝１，ｃ＝２）とし、スパンＳＰ２に対応したＤＣＭの分散補償量Ｄｄｃｍを−２００ｐｓ／ｎｍ（ｌ＝２，ｃ＝４）とし、スパンＳＰ３に対応したＤＣＭの分散補償量Ｄｄｃｍを−８００ｐｓ／ｎｍ（ｌ＝３，ｃ＝８）とする組合せが選択されたとすると、この場合に上記の（９）式〜（１２）式に用いられる指標ＶＡＲｄｃｍ［ｃ］は、図１０の下段に示すような値をとることになる。

Here, the arithmetic processing using the above equations (9) to (12) will be described in detail with a specific example. Here, for example, as shown in the upper part of FIG. 9, a wavelength path WP1 (i = 1) from the start node A to the end node D is assumed, and the DCM in the node B corresponding to the span SP1 between the nodes A and B is assumed. {−450, −400, −350} is set as a candidate, {−200, −150} is set as a DCM candidate in the node C corresponding to the span SP2 between the nodes B and C, and between the nodes C and D It is assumed that {−1000, −900, −800} is set as a DCM candidate in the node D corresponding to the span SP3. Then, as an optimal solution of the dispersion compensation amount of DCM for the wavelength path WP1 by the arithmetic processing in the previous step 14, for example, the dispersion compensation amount Ddcm of DCM corresponding to the span SP1 is set to −400 ps / nm (l = 1, c = 2), the dispersion compensation amount Ddcm of DCM corresponding to the span SP2 is -200 ps / nm (l = 2, c = 4), and the dispersion compensation amount Ddcm of DCM corresponding to the span SP3 is -800 ps / nm (l = 3, c = 8) is selected, the index VARdcm [c] used in the above equations (9) to (12) in this case has a value as shown in the lower part of FIG. I will take it.

  Then, when it is determined by the verification of the design result in step 21 that the design result for the wavelength path WP1 is unsuccessful, the constraint condition shown in the following expression (10) ′ is added in step 22. Become.

VARdcm [2] + VARdcm [4] + VARdcm [8]
≦ (NUMdcm [1] −1) (10) ′
Here, the number NUMdcm [1] of DCMs corresponding to the wavelength path WP1 is 3.

  As a result, the arithmetic processing executed returning to step 14, that is, the above equation (7) is applied as an objective function in the mixed integer programming, and the above equations (9) and (10) are used as constraints. In the arithmetic processing to which is applied, the combination of the chromatic dispersion compensation amounts of the wavelength path WP1 that has failed in the design in the previous processing is not selected as the optimum solution. Therefore, it is possible to perform highly accurate chromatic dispersion compensation design by repeatedly executing the above-described feedback processing until successful design for all wavelength paths set on the optical network is determined in step 21. Become.

  Regarding the above embodiments, the following additional notes are further disclosed.

(Supplementary note 1) On an optical network having a plurality of nodes connected to each other via an optical transmission line, on a plurality of wavelength paths indicating paths from the start node to the end node of the plurality of optical signals transmitted through the optical network A chromatic dispersion compensation design method for setting a compensation amount of chromatic dispersion compensation performed in
The process of entering optical network information;
Based on the optical network information, for each wavelength path, a process of setting a residual chromatic dispersion target value at the termination node;
A process of setting candidates for the amount of dispersion compensation in a plurality of wavelength dispersion compensators arranged on each wavelength path;
An operation for selecting the dispersion compensation amount of each chromatic dispersion compensator from the candidates so that the sum of errors between the residual chromatic dispersion value and the residual chromatic dispersion target value at the termination node for all wavelength paths is minimized. The process of executing the process;
A chromatic dispersion compensation design method comprising:

(Appendix 2) A chromatic dispersion compensation design method according to appendix 1,
The step of setting the residual chromatic dispersion target value includes setting the residual chromatic dispersion target value inside an intermediate portion of an allowable residual chromatic dispersion range at a terminal node of each wavelength path.

(Appendix 3) A chromatic dispersion compensation design method according to appendix 2,
The step of setting the residual chromatic dispersion target value sets the residual chromatic dispersion target value at the midpoint of the allowable residual chromatic dispersion range.

(Supplementary note 4) The chromatic dispersion compensation design method according to supplementary note 1, wherein
In the process of setting the dispersion compensation amount candidates, when each chromatic dispersion compensator is arranged at the input stage of the optical amplifier, the power of the optical signal that has passed through each chromatic dispersion compensator is input to the optical amplifier. A chromatic dispersion compensation design method, characterized in that a dispersion compensation amount candidate in each chromatic dispersion compensator is set so as to be within a dynamic range.

(Additional remark 5) It is a chromatic dispersion compensation design method of Additional remark 1, Comprising:
In the process of setting the dispersion compensation amount candidates, the residual chromatic dispersion target value at each node where each chromatic dispersion compensator is arranged is determined based on the residual chromatic dispersion target value at the terminal node of each wavelength path. A chromatic dispersion compensation design method, characterized in that a dispersion compensation amount corresponding to a range including all the set residual chromatic dispersion target values is set as a candidate for the chromatic dispersion compensator, set for each wavelength path passing through a node.

(Appendix 6) A chromatic dispersion compensation design method according to appendix 5,
In the process of setting the dispersion compensation amount candidates, when each chromatic dispersion compensator is arranged at the input stage of the optical amplifier, the power of the optical signal that has passed through each chromatic dispersion compensator is input to the optical amplifier. A chromatic dispersion compensation design method, characterized in that a dispersion compensation amount candidate in each chromatic dispersion compensator is set so as to be within a dynamic range.

(Supplementary note 7) The chromatic dispersion compensation design method according to supplementary note 1, wherein
In the process of setting the dispersion compensation amount candidates, the residual chromatic dispersion target value in each node where each chromatic dispersion compensator is arranged is set according to the span distance corresponding to the node, and the set residual compensation is set. A chromatic dispersion compensation design method, wherein a chromatic dispersion compensation amount corresponding to a chromatic dispersion target value and a range of error allowed for the chromatic dispersion target value is used as a candidate for the chromatic dispersion compensator.

(Appendix 8) A chromatic dispersion compensation design method according to appendix 7,
In the process of setting the dispersion compensation amount candidates, when each chromatic dispersion compensator is arranged at the input stage of the optical amplifier, the power of the optical signal that has passed through each chromatic dispersion compensator is input to the optical amplifier. A chromatic dispersion compensation design method, characterized in that a dispersion compensation amount candidate in each chromatic dispersion compensator is set so as to be within a dynamic range.

(Supplementary note 9) The chromatic dispersion compensation design method according to supplementary note 1, wherein
The process of executing the arithmetic processing is an objective function that the sum of errors between the residual chromatic dispersion value and the residual chromatic dispersion target value at the terminal node for all wavelength paths is minimized by linear programming, and A chromatic dispersion compensation design method for calculating an optimum solution of the dispersion compensation amount of each chromatic dispersion compensator, with the constraint that the dispersion compensation amount of each chromatic dispersion compensator is selected from the candidates .

(Additional remark 10) It is a chromatic dispersion compensation design method of Additional remark 1, Comprising:
Using the dispersion compensation amount of each chromatic dispersion compensator selected by the arithmetic processing, the optical transmission characteristics of each optical wavelength path are evaluated, and it is determined whether or not all wavelength paths satisfy a predetermined optical transmission characteristic. Process,
When there is a wavelength path that does not satisfy the predetermined optical transmission characteristic, a condition for deselecting the combination of dispersion compensation amounts selected for each chromatic dispersion compensator through which the wavelength path passes is added, and again, Arithmetic processing for selecting the dispersion compensation amount of each chromatic dispersion compensator from the candidates so that the sum of errors between the residual chromatic dispersion value at the terminal node and the residual chromatic dispersion target value for the wavelength path is minimized. And the process of performing
A chromatic dispersion compensation design method comprising:

(Supplementary Note 11) On an optical network having a plurality of nodes connected to each other via an optical transmission line, on a plurality of wavelength paths indicating paths from the start node to the end node of the plurality of optical signals transmitted through the optical network A chromatic dispersion compensation design system for setting a compensation amount of chromatic dispersion compensation performed in
An input means for inputting optical network information;
Target value setting means for setting a residual chromatic dispersion target value at the termination node for each wavelength path based on the optical network information input by the input means;
Candidate setting means for setting a dispersion compensation amount candidate in a plurality of chromatic dispersion compensators arranged on each wavelength path;
The dispersion compensation amount of each chromatic dispersion compensator is set so that the sum of errors between the residual chromatic dispersion value at the terminal node for all wavelength paths and the residual chromatic dispersion target value set by the target value setting means is minimized. Arithmetic means for executing arithmetic processing to select from candidates set by the candidate setting means;
A chromatic dispersion compensation design system comprising:

(Supplementary note 12) The chromatic dispersion compensation design system according to supplementary note 11, wherein
The chromatic dispersion compensation design system, wherein the target value setting means sets a residual chromatic dispersion target value inside an intermediate portion of an allowable residual chromatic dispersion range at a terminal node of each wavelength path.

(Supplementary note 13) The chromatic dispersion compensation design system according to supplementary note 12,
The chromatic dispersion compensation design system, wherein the target value setting means sets a residual chromatic dispersion target value at a midpoint of the allowable residual chromatic dispersion range.

(Supplementary note 14) The chromatic dispersion compensation design system according to supplementary note 11, wherein
When the chromatic dispersion compensators are arranged at the input stage of the optical amplifier, the candidate setting means is arranged so that the power of the optical signal that has passed through the chromatic dispersion compensators falls within the input dynamic range of the optical amplifier. In addition, a dispersion compensation amount candidate in each of the chromatic dispersion compensators is set.

(Supplementary note 15) The chromatic dispersion compensation design system according to supplementary note 11, wherein
The candidate setting means, based on a residual chromatic dispersion target value at a terminal node of each wavelength path set by the target value setting means, a residual chromatic dispersion target value at each node where each chromatic dispersion compensator is arranged Is set for each wavelength path passing through the node, and a dispersion compensation amount corresponding to a range including all the set residual chromatic dispersion target values is set as a candidate for the chromatic dispersion compensator. system.

(Supplementary note 16) The chromatic dispersion compensation design system according to supplementary note 15,
When the chromatic dispersion compensators are arranged at the input stage of the optical amplifier, the candidate setting means is arranged so that the power of the optical signal that has passed through the chromatic dispersion compensators falls within the input dynamic range of the optical amplifier. In addition, a dispersion compensation amount candidate in each of the chromatic dispersion compensators is set.

(Supplementary note 17) The chromatic dispersion compensation design system according to supplementary note 11, wherein
The candidate setting means sets a residual chromatic dispersion target value at each node where the chromatic dispersion compensators are arranged according to a span distance corresponding to the node, and sets the residual chromatic dispersion target value and the set residual chromatic dispersion target value. A chromatic dispersion compensation design system characterized in that a dispersion compensation amount corresponding to an allowable error range is set as a candidate for the chromatic dispersion compensator.

(Supplementary note 18) The chromatic dispersion compensation design system according to supplementary note 17,
When the chromatic dispersion compensators are arranged at the input stage of the optical amplifier, the candidate setting means is arranged so that the power of the optical signal that has passed through the chromatic dispersion compensators falls within the input dynamic range of the optical amplifier. In addition, a dispersion compensation amount candidate in each of the chromatic dispersion compensators is set.

(Supplementary note 19) The chromatic dispersion compensation design system according to supplementary note 11, wherein
The calculation means is configured to minimize the sum of errors between the residual chromatic dispersion value at the terminal node for all wavelength paths and the residual chromatic dispersion target value set by the target value setting means by linear programming. And calculating the optimum solution of the dispersion compensation amount of each chromatic dispersion compensator, with the constraint that the dispersion compensation amount of each chromatic dispersion compensator is selected from the candidates set by the candidate setting means A chromatic dispersion compensation design system.

(Supplementary note 20) The chromatic dispersion compensation design system according to supplementary note 11,
Using the dispersion compensation amount of each chromatic dispersion compensator selected by the computing means, the optical transmission characteristics of each optical wavelength path are evaluated, and it is determined whether or not all wavelength paths satisfy the predetermined optical transmission characteristics. Provided with evaluation judging means,
When the evaluation determining unit determines that there is a wavelength path that does not satisfy a predetermined optical transmission characteristic, the calculation unit is a combination of dispersion compensation amounts selected for each chromatic dispersion compensator through which the wavelength path passes. In order to minimize the sum of errors between the residual chromatic dispersion value at the terminal node for all wavelength paths and the residual chromatic dispersion target value set by the target value setting means again, A chromatic dispersion compensation design system for executing a calculation process for selecting a dispersion compensation amount of each chromatic dispersion compensator from candidates set by the candidate setting means.

It is a figure which shows the hardware constitutions in one Embodiment of the chromatic dispersion compensation design system by this invention. It is a figure which shows the example of a structure of the optical network with which this invention is applied, and an example of a dispersion compensation map. 3 is a flowchart showing an example of processing executed in the chromatic dispersion compensation design system of FIG. 1. It is a figure explaining the setting method of the DCM candidate by the 1st method about step 13 of FIG. It is a figure which shows an example of a DCM table. It is a figure explaining the setting method of the DCM candidate by the 2nd method about step 13 of FIG. It is a figure explaining the setting method of the DCM candidate by the 3rd method about step 13 of FIG. 6 is a flowchart showing an application example related to processing executed in the chromatic dispersion compensation design system of FIG. 1. It is a figure explaining the feedback process by steps 21 and 22 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Input device 12 ... Output device 13 ... Drive device 14 ... Auxiliary storage device 15 ... Memory device 16 ... Arithmetic processing device 17 ... Database 18 ... System bus 21, 25 ... Optical amplifier 22 ... Optical transmission line 23 ... Connector 24 ... Wavelength Dispersion compensator (DCM)
N1 to N7, A to J: Nodes WP1 to WP4 ... Wavelength paths SP1 to 9 ... Span RDtarget ... Residual chromatic dispersion target value

Claims (10)

For an optical network having a plurality of nodes connected to each other via an optical transmission line, wavelengths performed on a plurality of wavelength paths indicating paths from the start node to the end node of the plurality of optical signals transmitted through the optical network A chromatic dispersion compensation design method for setting a compensation amount of dispersion compensation,
The process of entering optical network information;
Based on the optical network information, for each wavelength path, a process of setting a residual chromatic dispersion target value at the termination node;
A process of setting candidates for the amount of dispersion compensation in a plurality of wavelength dispersion compensators arranged on each wavelength path;
An operation for selecting the dispersion compensation amount of each chromatic dispersion compensator from the candidates so that the sum of errors between the residual chromatic dispersion value and the residual chromatic dispersion target value at the termination node for all wavelength paths is minimized. The process of executing the process;
A chromatic dispersion compensation design method comprising: The chromatic dispersion compensation design method according to claim 1,
In the process of setting the dispersion compensation amount candidates, when each chromatic dispersion compensator is arranged at the input stage of the optical amplifier, the power of the optical signal that has passed through each chromatic dispersion compensator is input to the optical amplifier. A chromatic dispersion compensation design method, characterized in that a dispersion compensation amount candidate in each chromatic dispersion compensator is set so as to be within a dynamic range. The chromatic dispersion compensation design method according to claim 1,
In the process of setting the dispersion compensation amount candidates, the residual chromatic dispersion target value at each node where each chromatic dispersion compensator is arranged is determined based on the residual chromatic dispersion target value at the terminal node of each wavelength path. A chromatic dispersion compensation design method, characterized in that a dispersion compensation amount corresponding to a range including all the set residual chromatic dispersion target values is set as a candidate for the chromatic dispersion compensator, set for each wavelength path passing through a node. The chromatic dispersion compensation design method according to claim 1,
In the process of setting the dispersion compensation amount candidates, the residual chromatic dispersion target value in each node where each chromatic dispersion compensator is arranged is set according to the span distance corresponding to the node, and the set residual compensation is set. A chromatic dispersion compensation design method, wherein a chromatic dispersion compensation amount corresponding to a chromatic dispersion target value and a range of error allowed for the chromatic dispersion target value is used as a candidate for the chromatic dispersion compensator. The chromatic dispersion compensation design method according to claim 1,
The process of executing the arithmetic processing is an objective function that the sum of errors between the residual chromatic dispersion value and the residual chromatic dispersion target value at the terminal node for all wavelength paths is minimized by linear programming, and A chromatic dispersion compensation design method for calculating an optimum solution of the dispersion compensation amount of each chromatic dispersion compensator, with the constraint that the dispersion compensation amount of each chromatic dispersion compensator is selected from the candidates . The chromatic dispersion compensation design method according to claim 1,
Using the dispersion compensation amount of each chromatic dispersion compensator selected by the arithmetic processing, the optical transmission characteristics of each optical wavelength path are evaluated, and it is determined whether or not all wavelength paths satisfy a predetermined optical transmission characteristic. Process,
When there is a wavelength path that does not satisfy the predetermined optical transmission characteristic, a condition for deselecting the combination of dispersion compensation amounts selected for each chromatic dispersion compensator through which the wavelength path passes is added, and again, Arithmetic processing for selecting the dispersion compensation amount of each chromatic dispersion compensator from the candidates so that the sum of errors between the residual chromatic dispersion value at the terminal node and the residual chromatic dispersion target value for the wavelength path is minimized. And the process of performing
A chromatic dispersion compensation design method comprising: For an optical network having a plurality of nodes connected to each other via an optical transmission line, wavelengths performed on a plurality of wavelength paths indicating paths from the start node to the end node of the plurality of optical signals transmitted through the optical network A chromatic dispersion compensation design system for setting a compensation amount of dispersion compensation,
An input means for inputting optical network information;
Target value setting means for setting a residual chromatic dispersion target value at the termination node for each wavelength path based on the optical network information input by the input means;
Candidate setting means for setting a dispersion compensation amount candidate in a plurality of chromatic dispersion compensators arranged on each wavelength path;
The dispersion compensation amount of each chromatic dispersion compensator is set so that the sum of errors between the residual chromatic dispersion value at the terminal node for all wavelength paths and the residual chromatic dispersion target value set by the target value setting means is minimized. Arithmetic means for executing arithmetic processing to select from candidates set by the candidate setting means;
A chromatic dispersion compensation design system comprising: The chromatic dispersion compensation design system according to claim 7,
The candidate setting means, based on a residual chromatic dispersion target value at a terminal node of each wavelength path set by the target value setting means, a residual chromatic dispersion target value at each node where each chromatic dispersion compensator is arranged Is set for each wavelength path passing through the node, and a dispersion compensation amount corresponding to a range including all the set residual chromatic dispersion target values is set as a candidate for the chromatic dispersion compensator. system. The chromatic dispersion compensation design system according to claim 7,
The calculation means is configured to minimize the sum of errors between the residual chromatic dispersion value at the terminal node for all wavelength paths and the residual chromatic dispersion target value set by the target value setting means by linear programming. And calculating the optimum solution of the dispersion compensation amount of each chromatic dispersion compensator, with the constraint that the dispersion compensation amount of each chromatic dispersion compensator is selected from the candidates set by the candidate setting means A chromatic dispersion compensation design system. The chromatic dispersion compensation design system according to claim 7,
Using the dispersion compensation amount of each chromatic dispersion compensator selected by the computing means, the optical transmission characteristics of each optical wavelength path are evaluated, and it is determined whether or not all wavelength paths satisfy the predetermined optical transmission characteristics. Provided with evaluation judging means,
When the evaluation determining unit determines that there is a wavelength path that does not satisfy a predetermined optical transmission characteristic, the calculation unit is a combination of dispersion compensation amounts selected for each chromatic dispersion compensator through which the wavelength path passes. In order to minimize the sum of errors between the residual chromatic dispersion value at the terminal node for all wavelength paths and the residual chromatic dispersion target value set by the target value setting means again, A chromatic dispersion compensation design system for executing a calculation process for selecting a dispersion compensation amount of each chromatic dispersion compensator from candidates set by the candidate setting means.

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